[Tropical] Tropical Cyclone Discussion

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WTNT42 KNHC 192103
TCDAT2

Hurricane Fiona Discussion Number  22
NWS National Hurricane Center Miami FL       AL072022
500 PM AST Mon Sep 19 2022

The hurricane is beginning to move away from the Dominican Republic
and over the warm waters of the Atlantic north of Hispaniola.
Fiona's cloud pattern is well organized and its inner core is
becoming better defined with very cold cloud tops becoming
concentrated near the eye.  Upper-level outflow is strong over most
of the circulation.  The current intensity estimate is set at 85 kt
which is a little below the latest Dvorak estimates from TAFB and
SAB.  An Air Force Reserve Unit Hurricane Hunter aircraft is
scheduled to investigate the system in a few hours, and assess its
structure and intensity.

Fiona continues to move northwestward, at a slightly faster forward
speed, or at about 325/9 kt.  There is little change to the track
forecast philosophy from the previous few advisory packages.
During the next couple of days, the hurricane is expected to
gradually turn toward the north while moving along the western
periphery of a mid-level subtropical anticyclone.  In 3-5 days,
Fiona should turn toward the north-northeast and accelerate in
response to a vigorous mid-tropospheric trough near the northeast
coast of the United States.

Global model forecasts continue to show moderate upper-level
west-southwesterly flow over Fiona while it moves over the
southwestern Atlantic early this week.  Although this flow should
cause some shear over the hurricane during the next couple of
days, the intensity guidance models indicate that this shear will
not be strong enough to prevent further intensification.  The
official intensity forecast has been increased a little more for
this advisory and is in good agreement with the latest LGEM
guidance.  It now appears that Fiona will become a major hurricane
sooner than previously forecast.

Near the end of the forecast period, as the system becomes more
embedded within the  mid-latitude flow and interacts with the
strong mid-tropospheric trough, it should be making the transition
into a vigorous extratropical cyclone.  This is also suggested by
the latest FSU cyclone phases analyses.

Key Messages:

1.  Heavy rains from the trailing bands of Fiona will continue
across Puerto Rico through this evening, and across the eastern
Dominican Republic through tonight.  These rains could produce
life-threatening and catastrophic flooding along with mudslides and
landslides across Puerto Rico and eastern portions of the Dominican
Republic.

2. Hurricane conditions are expected over the Turks and Caicos, with
tropical storm conditions over the southeastern Bahamas, beginning
late tonight or early Tuesday.

3.  Interests in Bermuda should monitor the progress of Fiona.


FORECAST POSITIONS AND MAX WINDS

INIT  19/2100Z 20.1N  69.8W   85 KT 100 MPH
 12H  20/0600Z 21.2N  70.5W   95 KT 110 MPH
 24H  20/1800Z 22.8N  71.1W  100 KT 115 MPH
 36H  21/0600Z 24.1N  71.3W  110 KT 125 MPH
 48H  21/1800Z 25.7N  71.0W  115 KT 130 MPH
 60H  22/0600Z 27.6N  70.2W  115 KT 130 MPH
 72H  22/1800Z 29.9N  68.9W  110 KT 125 MPH
 96H  23/1800Z 37.0N  62.3W  105 KT 120 MPH
120H  24/1800Z 48.5N  58.5W   80 KT  90 MPH

$$
Forecaster Pasch
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